The present invention relates to a method of making a chassis for a vehicle and to a chassis made with extruded beams that are connected by extruded couplers.
A chassis is the backbone of a vehicle that provides a durable frame to which the body, drive train and other parts of a vehicle are assembled. A conventional vehicle chassis is formed of welded, stamped or forged steel beams that add considerable weight to a vehicle. With conventional steel chassis, it is a constant challenge to consistently form and assemble the chassis parts to meet close tolerances. The weight of a conventional chassis adversely impacts fuel economy. Recently, efforts have been made to eliminate conventional steel chassis.
One approach that addresses the disadvantages of a separate conventional steel chassis is the development of uni-body construction techniques wherein frame members are formed integrally with body parts that are assembled together to form the frame. With uni-body construction, different modules are integrally formed with portions of the frame that are then linked together by fasteners or welding. One challenge encountered with a uni-body type chassis includes maintaining close tolerances for proper vehicle fit and finish requirements. In the event that a uni-body vehicle is involved in a collision, it may be difficult or impossible to straighten the integral frame without adversely impacting other body panels.
Space frame construction techniques use welded steel or aluminum tubular members that are assembled together to manufacture some vehicles. However, space frame vehicles tend to be expensive to manufacture due to labor costs and extensive fixturing required to meet tolerances. One recent development relating to space frames is disclosed in U.S. Pat. No. 5,947,519 that proposes the use of specialized nodes to which frame rails are welded. The ends of frame members are peripherally welded to the node during the assembly process. Welding aluminum is a relatively expensive process requiring special aluminum welding rods. Welding causes localized heating of the rails and nodes that can result in deformation of chassis parts. Also, the approach disclosed in this patent does not provide an easy way to align frame rails to assure maintenance of close tolerances without the use of expensive assembly fixtures.
The present invention addresses the above problems and shortcomings of the prior art and provides a simple method of making a chassis and an improved chassis construction with additional benefits and advantages as summarized below.
According to the present invention, a method of manufacturing a chassis for a vehicle is provided. The method comprises extruding a plurality of beams, the beams having walls defining an internal surface. Beams are formed in different lengths depending upon the size of the chassis to be built. A plurality of couplers are extruded and have at least two generally horizontally extending receptacles sized to fit within the walls of the beam. Each coupler has a generally vertically oriented pocket formed between the receptacles. The couplers are assembled between beams by assembling the beams and couplers together loosely and to a fixture. The fixture has locating pins located at predetermined locations that are received in the pockets of the couplers. The beams and couplers are then permanently affixed to each other to form the chassis.
The step of securing the beams and couplers together is preferably performed by applying an aluminum bonding cement between the receptacles of the couplers and the beams. Alternatively, the beams and couplers could be secured together by forming holes in the ends of the beams and in corresponding locations on the couplers and inserting fasteners through the holes. The beams and couplers can also be assembled together by means of both cement and mechanical fasteners to provide a redundant securing system that may be desirable in some applications.
According to another feature of the present invention, the couplers are preferably extruded so that the receptacles have a closed end that is first inserted into one of the beams.
According to another aspect of the present invention, the couplers and/or beams may be formed with a recess having ribs extending in the direction of extrusion formation to facilitate the flow of cement between the receptacles and the beam. The ribs provide additional bonding surface area and additional surface structure that enhances bond strength.
According to yet another aspect of the present invention, the step of extruding the couplers may further include the step of extruding the coupler to form a pillar of the vehicle that extends upwardly from the beams that are joined by the coupler. The receptacle is separated from the pillar by cutting away a portion of the coupler for receiving a wall of the beam.
The method of the present invention may also include, as part of the step of extruding the coupler, forming a stop rib on the receptacles at the juncture of the receptacles and the central portion of the coupler.
The present invention also comprehends a chassis for a vehicle that is formed in five modules. A center chassis module is provided to which the fire wall bulkhead of the vehicle and passenger compartment of the vehicle are secured. A drive train and front suspension module is provided to which the engine, transmission and front suspension components are attached. The drive train module is secured to the front end of the center chassis module. The rear suspension and gas tank are secured to the rear suspension module. The rear suspension module is secured to the rear end of the center chassis module. A front crush module is attached to the drive train and front suspension module and includes a front bumper assembly. A rear crush module, including a rear bumper assembly, is separate from but secured to the rear suspension module. The chassis from front to rear includes the front crush module, the drive train and front suspension module, the center chassis module, the rear suspension module and the rear crush module.
According to the present invention, a passenger compartment trim ring may be provided as part of the vehicle that is assembled to the drive train and front suspension module, center chassis module and rear suspension module. The trim ring is a mid-body superstructure that forms a combined dashboard, two rocker panel covers and a well for a convertible top of the vehicle.
The unique modular chassis of the present invention is formed by at least one transverse rear beam that is connected on opposite sides to two rear couplers. Two side beams are connected on their back ends to each of the two rear couplers and two front couplers are connected to the front ends of each of the two side beams. Two convergent front beams are connected to the front couplers on their outer back ends and to the drive train and front suspension module on their forward ends.
According to yet another aspect of the present invention, the rear beam is preferably formed in two sections that are joined to a central drive shaft tunnel bracket.
A pair of hinge pillars may be assembled to the front couplers with one hinge pillar being secured to each of the front couplers to extend upwardly to the base of the windshield frame.
According to another aspect of the present invention, the couplers may connect adjacent beams in a range of angular orientations from 0 to 180 degrees. However, the couplers may connect beams at approximately 90 degrees or approximately 135 degrees. By approximately, it is intended that the angular orientations be within 15 degrees of 90 or 135 degrees.
According to another unique feature of the invention, the coupler may include a pillar of the vehicle that extends upwardly from the receptacle. The pillar is formed above the receptacle of the coupler over which the beam is received.
A further aspect of the invention is the concept of forming a stop rib on the receptacles of the couplers at the juncture of the receptacles and the central portion of the coupler.
Another feature of the present invention relates to the structure and function of the coupler used in forming the chassis. The coupler includes a central portion having an outer wall and a plurality of inner walls extending inwardly from the outer wall to a pocket that is connected to the inner walls. At least two receptacles are connected to and extend outwardly from the central portion. The receptacles are dimensioned to be received in the central opening of one of the extruded beams. The central pocket is adapted to be placed on a locating pin of a fixture that is used to align the coupler with the extruded beams and other couplers. The central opening in the extruded beam may be rectangular in shape and that the receptacles would in turn be rectangular in shape having a closed end that is formed as an extruded wall on the opposite side of the receptacle from the central portion. The receptacle also includes two side walls that are formed as extruded walls connecting the end wall to the central portion.
As explained above in the context of the chassis construction, the couplers may be formed with a wide variety of angular relationships between receptacles. The couplers may include recesses having ribs extending in the direction of the extrusion to facilitate flow of cement and augment bonding as described above. Likewise, the coupler may include a pillar of the vehicle that extends upwardly from the receptacle. The couplers may include stop ribs formed on the receptacles.
These and other advantages and features of the present invention will be apparent to one of ordinary skill in the art in view of the attached drawings and following detailed description.